Applying async/await feature to ArcGIS API for JavaScript code?

Question

How do I apply the async/await feature to this code? I need to wait for the reltionshipQuery and forEach to finish before I return contentSpecies.

 contentSpecies = function(value, key, data) {
 var contentSpecies = [];
 objectID = data.OBJECTID;
 var queryTask = new QueryTask({
 url: "https://webmaps.com/MapServer/1"
 });
 var relationQuery = new RelationshipQuery({
 objectIds: [objectID],
 outFields: ["Species", "Notes", "Status"],
 returnGeometry: true,
 relationshipId: 0
 });
 queryTask.executeRelationshipQuery(relationQuery)
 .then(function(rslts) {
 var features = rslts[objectID].features;
 features.forEach(function(ftr) {
 var t = ftr.attributes;
 var species = t.Species;
 contentSpecies += "<span class='bold' title='Species'><b>Species: </b></span>" + species + "<br/>";
 var notes = t.Notes;
 contentSpecies += "<span class='bold' title='Notese'><b>Notes: </b></span>" + notes + "<br/>";
 var status = t.Status;
 contentSpecies += "<span class='bold' title='Status'><b>Status: </b></span>" + status + "<br/>";
 });
 //return contentSpecies;
 })
 return contentSpecies
 }

Answer 1

contentSpecies = async function(value, key, data) {
 try {
 ...
 let rslts = await queryTask.executeRelationshipQuery(relationQuery);
 var features = rslts[objectID].features;
 features.forEach(function(ftr) {
 ...
 } catch(e) {
 console.error(e);
 }
}

• Jay Hill: it is not executing. can't even get a console log to work.

Answer 2

async function xxx(){ 
 var results = await queryTask.executeRelationshipQuery(relationQuery)
}

It works for me - see Using async await in ArcGIS JavaScript API